Clinicians have yet another type of multidrug-resistant (MDR) bacteria to put on the radar screen: MDR Bacteroides fragilis.

Bacteroides fragilis strains are obligate anaerobic bacteria that live in the human gut. They’re usually susceptible to metronidazole, carbapenems, and beta-lactam antibiotics, especially in the United States. But last May, a US resident in his 70s who recently had traveled to India was diagnosed with B fragilis infection that did not respond to treatment with several antibiotics, including metronidazole, imipenem, piperacillin/tazobactam, and clindamycin.